The present invention relates generally to light strips and, more particularly, to a system and method for manufacturing a continuous light strip with light emitting diodes that minimizes manufacturing costs and that includes built-in manufacturing flexibility to produce a light strip with a configuration tailored to specific customer parameters.
Light emitting diode (LED) light strips provide usual markings in dimly lit environments. LED light strips are relatively inexpensive, easy to install, and exhibit long life when compared to similar bulb or lamp based markers.
Regardless of the light strip application, it is imperative that the LED and associated circuitry housed within the strip is protected from damage due to excessive loads placed on the strip and from exposure to moisture ingress. However, many conventional LED light strips include circuitry housed within hollow tube-like sheathings which provide only minimal protection against mechanical damage to the circuitry due to excessive loads placed on the sheathings. Also, as the tube-like sheathings are hollow, the LED strips are typically susceptible to damage caused by moisture penetration. As a result, such light strips are often not desirable for outdoor lighting applications or other applications in which the strips are exposed to extreme weather conditions or abuse.
Another conventional light strip includes a multi-layer electroluminescent (EL) lamp configuration sealed through a conventional sheet or hard lamination process. In this hard lamination process, a top layer of protective film is either adhesively bonded or thermally fused to a bottom layer of protective film through the use of high temperatures and high pressure rollers to sandwich the EL lamp configuration between the layers. Such an EL light strip provides a more permanent type of protective sheathing than the above mentioned tube-like sheathing associated with other conventional EL light strips, and provides a more effective moisture barrier.
However, moisture is often capable of penetrating into the interior of these two-piece EL light strips through the fused or bonded seal joining the two-piece housing, especially when the strips are used in outdoor applications, or after the bonded or fused seal connecting the two-piece housing weakens over time. In addition, the hard lamination process used to seal the EL lamp configuration is not desirable for LED circuitry, as LEDs are typically greater in height than the substantially flat layers forming the EL lamp configuration. High pressure rollers typically used to bond or fuse the two-piece housing could crush the protruding LEDs during formation of the strip. In addition, the high temperatures required for the bonding or fusing of the strip would subject the LEDs and associated circuitry to heat damage.
In response to the aforementioned limitations associated with conventional light strips, integral LED light strips formed through a continuous extrusion process have been developed. Such integrally formed strips are single-piece strips that have no internal voids, and thereby provide a high degree of protection against damage due to loads placed on the strips and are highly resistant to moisture ingress. Examples of such integrally formed strips are disclosed in pending U.S. patent application Ser. No. 08/520,237 entitled xe2x80x9cIntegrally Formed Linear Light Strip With Light Emitting Diodesxe2x80x9d assigned to StanTech, of Dearborn, Mich., and in pending U.S. patent application Ser. No. 08/707,212 entitled xe2x80x9cIntegrally Formed Linear Light Strip with Light Emitting Diodes,xe2x80x9d also assigned to StanTech.
While the above mentioned integrally formed LED light strips exhibit desirable characteristics, there is still a need for further improvement in the art. In particular, there is a need to provide a programmable LED light strip manufacturing system and method whose parameters may be varied according to particular light strip requirements. There is also a need for an LED light strip that requires no circuitry preassembly, thereby minimizing manufacturing costs through automation of the LED circuit assembly process. There is also a need for an LED light strip in which light strip connectors are also integrally formed with discrete segments of the light strip itself, thereby minimizing overall system cost and the need for external commercial light strip connectors. Further, there is a need for an integrally formed LED light strip that includes fully encapsulated LED circuitry connected to a substrate that exhibits superior bonding characteristics with the extruded light strip housing, thereby providing a high degree of protection from moisture ingress and thereby increasing the functional life of the strip itself.
Accordingly, the present invention provides a continuously and integrally formed single piece light strip having no internal voids that allows a continuous length of substrate populated with LED light circuits to be fed into an extruder that encapsulates the substrate and circuits thereon. The light strip of the present invention is assembled through a computer-controlled method and system that has control parameters that may be easily changed to tailor the features of the manufactured light strip to the particular design parameters of a customer. The LED light strip requires no circuit preassembly, thereby minimizing manufacturing costs through automation of the LED circuit assembly process. The present invention also provides an LED light strip including light strip connectors integrally formed with the light strip itself, thereby minimizing overall system cost and the need for external commercial light strip connectors. In addition, the present invention provides an integrally formed LED light strip that includes a continuous plurality of LED circuits connected to a substrate that exhibits superior bonding characteristics with the continuously extruded and protective housing, and thereby provides a high degree of protection from moisture ingress, thereby increasing the functional life of the strip itself.
In particular, the present invention relates to a continuously and integrally formed single-piece light strip that includes a substrate having a plurality of populated light circuits. A plurality of bus elements spaced apart from one another at a predetermined distance are adhered to the substrate and are in electrical communication with the plurality of light circuits. A continuously extruded plastic material completely encapsulates the bus elements and the plurality of light circuits to form a protective housing over the bus elements and the light circuits.
The present invention also relates to a system for forming the above integral light strip. The system includes a circuit supply subsystem that supplies a continuous length of populated light circuits. The system also includes an extrusion subsystem that receives the continuous length of populated light circuits from the circuit supply subsystem and that extrudes a protective thermoplastic housing over the continuous length of populated light circuits.